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PubMed This is a summary of 14 peer-reviewed journal articles Updated
Dermatology

The Subtypes: Macular, Lichen, Nodular, and Biphasic

At a Glance

Primary cutaneous amyloidosis has four subtypes: macular (flat, dark patches), lichen (itchy, raised bumps), biphasic (a mix of both), and nodular (firm lumps). Most stem from skin cell damage due to scratching, but the rare nodular type involves immune proteins and requires systemic testing.

Primary Cutaneous Amyloidosis (PCA) is not a single disease, but rather a group of conditions. While they all involve the buildup of abnormal proteins in the skin, doctors divide them into distinct subtypes [1][2]. Identifying your specific subtype is essential because it explains why your skin looks the way it does, dictates your Treatment Strategies, and determines what kind of monitoring you may need [3][4].

Macular and Lichen Amyloidosis: The Keratin Connection

The two most common forms, macular and lichen amyloidosis, share a similar biological origin. The amyloid protein comes from keratinocytes, the primary cells in your outer layer of skin [5][6]. When these cells are damaged—often by chronic scratching or friction—they break down and release keratin filaments that the body mistakenly packs into amyloid deposits [5][7].

  • Macular Amyloidosis:

    • Appearance: Characterized by flat, darkened (hyperpigmented) patches of skin, often with a distinct “rippled” or “salt-and-pepper” pattern [1][8].
    • Common Locations: Frequently found on the upper back, chest, and arms [1][9].
    • Symptoms: While mildly itchy, the primary concern is often the darkened appearance of the skin [9].

  • Lichen Amyloidosis:

    • Appearance: Small, firm, raised bumps (papules) that may join together to form thickened, scaly plaques [1][4].
    • Common Locations: It typically appears on the shins or the outer parts of the arms and legs [1][9]. However, it can also appear on the upper back (which is sometimes linked to extremely rare genetic conditions—see Systemic Risk and Rare Associations).
    • Symptoms: It is notoriously itchy (pruritic). The intense itch leads to more scratching, thickening the skin over time [1][7].

  • Biphasic Amyloidosis:

    • It is very common for patients to have a combination of both macular and lichen amyloidosis occurring at the same time [1]. If your pathology report lists “Biphasic Amyloidosis,” it simply means you have both flat, darkened patches and raised, itchy bumps.

Nodular Amyloidosis: A Distinct Biological Path

Nodular amyloidosis is the rarest subtype and is biologically different [4][2]. Instead of being made from damaged skin cells, the amyloid in this type is made from immunoglobulin light chains—proteins typically produced by immune cells [10][11].

  • Appearance: Firm, often painless, skin-colored, pink, or yellowish lumps (nodules) or thick plaques [12][13].
  • Common Locations: Can appear anywhere, including the face, trunk, genitals, or extremities [12][14].
  • The Systemic Distinction: Because “light-chain” amyloid is the same protein involved in serious whole-body conditions, patients with the nodular subtype require a medical “work-up” to ensure the protein is only being produced locally in the skin [11][3].

Common questions in this guide

What is the difference between macular and lichen amyloidosis?
Macular amyloidosis causes flat, darkened patches of skin that are usually mildly itchy. In contrast, lichen amyloidosis creates intensely itchy, firm, raised bumps that can combine to form thickened, scaly plaques.
What does it mean if I have biphasic amyloidosis?
Biphasic amyloidosis means you have a combination of both the macular and lichen subtypes at the same time. You will experience both the flat, hyperpigmented patches and the raised, itchy bumps on your skin.
What causes the amyloid protein to build up in my skin?
In macular and lichen amyloidosis, the protein buildup often results from chronic scratching or friction. This repetitive friction damages the outer skin cells, causing them to release keratin that the body mistakenly packs into amyloid deposits.
Why does nodular amyloidosis require special testing?
Unlike other types caused by skin damage, nodular amyloidosis is made from immune system proteins. Because these specific proteins can sometimes be involved in serious whole-body conditions, doctors must perform extra tests to ensure the buildup is isolated to your skin.

Questions to Ask Your Doctor

Curated prompts to bring to your next appointment.

  1. 1.Does my pathology report show 'keratin-derived' amyloid or 'light-chain' amyloid?
  2. 2.Based on the appearance of my skin, do I have the biphasic subtype?
  3. 3.Are the locations of my lesions typical for this specific subtype?

Questions For You

Tap a prompt to share your answer — we'll use it plus this page's context to start a tailored conversation.

References

References (14)
  1. 1

    Refractory cutaneous lichen amyloidosis coexisting with atopic dermatitis responds to the Janus Kinase inhibitor baricitinib.

    Xia D, Xiao Y, Li M, Li W

    Dermatologic therapy 2022; (35(9)):e15724 doi:10.1111/dth.15724.

    PMID: 35855568
  2. 2

    Clinical resolution of generalized lichen amyloidosis with dupilumab: a new alternative therapy.

    Humeda Y, Beasley J, Calder K

    Dermatology online journal 2020; (26(12)).

    PMID: 33423428
  3. 3

    [Endogenous skin overloads].

    Ortonne N

    Annales de pathologie 2024; (44(6)):476-485 doi:10.1016/j.annpat.2024.09.006.

    PMID: 39368935
  4. 4

    Diagnosing of primary cutaneous amyloidosis using dermoscopy and reflectance confocal microscopy.

    Lei W, Ai-E X

    Skin research and technology : official journal of International Society for Bioengineering and the Skin (ISBS) [and] International Society for Digital Imaging of Skin (ISDIS) [and] International Society for Skin Imaging (ISSI) 2022; (28(3)):433-438 doi:10.1111/srt.13143.

    PMID: 35188697
  5. 5

    34βE12 is the Most Reliable Marker for Keratin-Derived Cutaneous Amyloid: A Comparative Study.

    Daruish M, Al-Sharbatee G, D'Arrigo C, Taibjee S

    The American Journal of dermatopathology 2025; (47(6)):439-441 doi:10.1097/DAD.0000000000002942.

    PMID: 39983073
  6. 6

    Primary cutaneous amyloidosis: A clinicopathological, histochemical, and immunohistochemical study.

    Sinha A, Manjunath GV, Basavaraj V

    Indian journal of pathology & microbiology 2021; (64(2)):323-328 doi:10.4103/IJPM.IJPM_32_20.

    PMID: 33851627
  7. 7

    Secondary Localized Cutaneous Amyloidosis is not Rare in Bowen's Disease and Bowenoid Papulosis.

    Baykal C, Hurdogan O, Kobaner GB, et al.

    Turk patoloji dergisi 2022; (38(1)):54-59 doi:10.5146/tjpath.2021.01530.

    PMID: 34514563
  8. 8

    Image Gallery: Dermoscopy of lichen amyloidosis.

    Moscarella E, Ronchi A, Agozzino M, et al.

    The British journal of dermatology 2018; (179(6)):e231 doi:10.1111/bjd.17109.

    PMID: 30508246
  9. 9

    Pathophysiology of pruritus in primary localized cutaneous amyloidosis.

    Tey HL, Cao T, Nattkemper LA, et al.

    The British journal of dermatology 2016; (174(6)):1345-50 doi:10.1111/bjd.14391.

    PMID: 26748444
  10. 10

    Nodular Cutaneous Amyloidosis on the Nose Confirmed Using Electron Microscopy: A Case Report.

    Choi GW, Kim DH

    Annals of dermatology 2023; (35(Suppl 2)):S376-S377 doi:10.5021/ad.22.075.

    PMID: 38061751
  11. 11

    A suspicious nodule in a toe web space.

    Gilbert G, Wiggins J, Biswas A, Gupta G

    Clinical and experimental dermatology 2025; (50(8)):1704-1706 doi:10.1093/ced/llaf113.

    PMID: 40059631
  12. 12

    Detailed primary localised cutaneous nodular amyloidosis clinical and pathological workup.

    Ayub M, Kaminoff L, Maity A, Ali Z

    BMJ case reports 2024; (17(11)) doi:10.1136/bcr-2024-262126.

    PMID: 39532322
  13. 13

    A Peculiar Case of Large and "Unresectable" Primary Localized Cutaneous Nodular Amyloidosis of the Ankle.

    Stanizzi A, Torresetti M, Barbisan F, et al.

    Case reports in dermatology 2021; (13(3)):502-505 doi:10.1159/000519030.

    PMID: 34899232
  14. 14

    Primary Localized Cutaneous Nodular Amyloidosis on a Toe: Clinical Presentation, Histopathology, and Dermoscopy Findings.

    Ferreira ILO, Fernandes EL, Lapins J, et al.

    Dermatology practical & conceptual 2019; (9(3)):235-236 doi:10.5826/dpc.0903a18.

    PMID: 31384506

This page explains primary cutaneous amyloidosis subtypes for educational purposes only. Always consult your dermatologist to understand your specific diagnosis and pathology report.

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